Yes it is. Although just a hunch, kH will prevent the CO2 to be available in the water making BBA thrive. That, or BBA feeds on kH which is not unusual for an algae to do.
After trying several methods of eradicating it in my tank, I found that lowering the kH stopped its spread and now looks like it's retreating. Slowly, but at least it stopped spreading.
I use RO water only in my planted tanks. It's easy for me to mess with kH and gH either up or down.